BRUSSELS — Salah Abdeslam, believed to be the only direct participant in the November attacks in Paris who is still alive, told investigators on Saturday after being captured a day earlier that he wanted to detonate his suicide vest at the Stade de France soccer stadium on the night of the attacks but “backed out,” said the lead terrorism prosecutor in France.

Three of the attackers detonated their vests there, but killed just one person and themselves on Nov. 13 during a match between France and Germany.

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Sven Mary, the Belgian lawyer of Paris attacks suspect Salah Abdeslam, talks to the media outside the building of the Federal Police in Brussels on Saturday.CreditAurore Belot/Agence France-Presse — Getty Images

The prosecutor, François Molins, warned against putting too much stock in anything Mr. Abdeslam said at such an early stage. “These first statements leave unanswered a whole series of questions that Salah Abdeslam will have to answer,” he said.

At a hearing before a judge in Belgium on Saturday, Mr. Abdeslam made it clear that he would fight extradition to France, said his lawyer, Sven Mary.

Mr. Mary spoke to journalists after he and Mr. Abdeslam met with a Belgian magistrate who was to decide whether to issue a formal arrest warrant against Mr. Abdeslam, who is accused of playing a key role in the Nov. 13 attacks on a concert, cafes and a stadium that killed 130 people.

Later Saturday, the magistrate issued the warrant, the federal prosecutor’s office said.

Mr. Abdeslam was captured with another person suspected of being an accomplice, and both were taken to a Brussels hospital. They were discharged early Saturday, Yvan Mayeur, the Brussels mayor, said on Twitter.

Mr. Abdeslam, a French citizen, is subject to a European arrest warrant issued by France. His seizure in the Brussels neighborhood of Molenbeek after he spent four months on the run brought relief to people who had seen his wanted poster all over two countries for months.

Bernard Cazeneuve, the French interior minister, said Saturday that he hoped Mr. Abdeslam could be delivered to France to face justice. He spoke after President François Hollande held an emergency security meeting in Paris.

Mr. Hollande has warned that more arrests will come as the authorities try to dismantle a network involved in the attacks that is much larger than originally suspected. The Islamic State, also known as ISIS or ISIL, claimed responsibility for the Paris attacks.

There are worries in Belgium about more attacks , in part because in one of the Brussels apartments where Mr. Abdeslam’s fingerprints were found, the police found an ISIS flag as well as a large amount of ammunition. The flag is often used as a prop in martyrdom videos filmed by participants in attacks before an operation.

Mr. Cazeneuve called Mr. Abdeslam’s arrest a “major blow” to the Islamic State group in Europe, but warned that the threat of new attacks was “extremely high.”

Belgium’s prime minister, Charles Michel, also said that “the fight is not over,” and the government announced that the nation’s terrorism alert level was unchanged at three on a four-point scale. Interpol, the world police body, urged greater vigilance at all of Europe’s borders to catch any of Mr. Abdeslam’s accomplices or those planning new attacks if they try to flee Europe.

A Belgian prosecutor, Eric Van der Sypt, said that with an arrest warrant, Mr. Abdeslam would have to appear before a pretrial court that would decide whether he stays in jail for up to a month.

A version of this article appears in print on , on Page A13 of the New York edition with the headline: Paris Suspect Claims He ‘Backed Out’ of Stadium Bombing, Prosecutor Says. Order Reprints | Today’s Paper | Subscribe